What air pressure is right

[J Ingersoll]

I've just upgraded my GYM's to Maxxis M8008 ST225/LR15 load range E tires on our 25' Safari. They have a maximum pressure of 80lbs. I am inclined to run them at the factory recommended 65 lbs. Does anyone think they will be under inflated at 65lbs?

[jimmini]

Just yesterday I noted that some of the ST tire makers on their web sites say to inflate them to MAX PSI that is on the side wall. This varies by load range of tire.

I just got new ST tires and the dealer would not inflate them to the 55 PSI on trailer data plate, He would only inflate them to MAX on side wall on mine that is 80 PSI. So that is what I now run, we will see it tires last longer before they fail.

[SeaLevel]

Originally Posted by J Ingersoll

I've just upgraded my GYM's to Maxxis M8008 ST225/LR15 load range E tires on our 25' Safari. They have a maximum pressure of 80lbs. I am inclined to run them at the factory recommended 65 lbs. Does anyone think they will be under inflated at 65lbs?

How much weight are they carrying? According to their tire pressure chart, 65psi would be like load range D - 2540lbs. Maybe something in the low 70s would be appropriate?

http://www.maxxis.com/trailer/traile...nflation-chart

[Boxite]

ST tires have a lousy reputation with many because they have a failure-rate that is caused by underinflation.
ST tires carry heavier loads vs tire-size because they have heavier-gauge steel wire beads and belts and heavier fabric cords used in construction. If those are not supported by the tire's rated pressure they will flex excessively, build heat, and fail. Then the owner bad-mouths the ST tires because they didn't go as far as their vehicle tires which are built for pressures which allow sidewall flex for ride-comfort.

Run ST tires at their rated sidewall-placarded pressures....not according to commonly misunderstood loading charts intended for passenger vehicles.

[jimmini]

Here is info on ST tires
Discount tire inflate to MAX PSI on side wall
http://www.discounttire.com/dtcs/inf...erTireFacts.do


Inflate to MAX

https://www.etrailer.com/faq-trailer...questions.aspx

[Mrjkq]

I have the same tires installed in April of this year pulling a 25ft Flying Cloud. I inflated them to 75lbs with nitrogen rather than air and recently completed a 10,150 mile trip sometime in very hot 100%+ temperatures. I left that 5 Lb gap to allow for expansion and drove at 65mph maximum for the entire trip. They handled my 7100 Lbs without a flaw. IMHO, any less inflation could & probably would eventually cause tire failure, especially in that heat.

[franklyfrank]

Originally Posted by J Ingersoll

I've just upgraded my GYM's to Maxxis M8008 ST225/LR15 load range E tires on our 25' Safari. They have a maximum pressure of 80lbs. I am inclined to run them at the factory recommended 65 lbs. Does anyone think they will be under inflated at 65lbs?

What made you decide to go with ST tires?

[jimfa440]

I ran my Maxis tires at 65 psi on a 30' Excella. No problems at that pressure.

[Larry C]

I would think that the main reason to go to load range E tires would for the increased weight capacity. In order to realize that increase capacity the maximum recommended pressure is 80 psi for load range E tires.

If you inflate to 65, you might have well stayed with your GYMs and inflated them to 65 psi..

Some people deliberately under inflate by a few pounds to "compensate" for increase tire pressure due to heat build up.....all they are doing is starting out with an under inflated tire, which will be more prone to failure because there will be more heat build up.

Some people drink the Kool Aid about nitrogen instead of compressed air....the air we breath is 70% nitrogen, you've got to be kidding me if you think that additional 30% nitrogen is going to make a difference? The theory is that nitrogen doesn't expand as quickly as compressed air in high temps......maybe so, maybe not......at any rate it's a waste of dollars.

People should stop trying to read more into this problem than exists....

For whatever it's worth..

Larry C

[Starlight Mike]

Originally Posted by J Ingersoll

I've just upgraded my GYM's to Maxxis M8008 ST225/LR15 load range E tires on our 25' Safari. They have a maximum pressure of 80lbs. I am inclined to run them at the factory recommended 65 lbs. Does anyone think they will be under inflated at 65lbs?

I have always been told by dealers to put the max air in, if it says 80, I put in 80.
I am now moving up to LT tires at the suggestion of many in this forum. I did not have good luck with ST tires even when told how to properly inflate.

[banderabob]

I run 65psi in my Carlisles as recommended.

[Boxite]

Originally Posted by Larry C

I would think that the main reason to go to load range E tires would for the increased weight capacity. In order to realize that increase capacity the maximum recommended pressure is 80 psi for load range E tires.

If you inflate to 65, you might have well stayed with your GYMs and inflated them to 65 psi..

Some people deliberately under inflate by a few pounds to "compensate" for increase tire pressure due to heat build up.....all they are doing is starting out with an under inflated tire, which will be more prone to failure because there will be more heat build up.

Some people drink the Kool Aid about nitrogen instead of compressed air....the air we breath is 70% nitrogen, you've got to be kidding me if you think that additional 30% nitrogen is going to make a difference? The theory is that nitrogen doesn't expand as quickly as compressed air in high temps......maybe so, maybe not......at any rate it's a waste of dollars.

People should stop trying to read more into this problem than exists....

For whatever it's worth..

Larry C

Well, Larry... You're wrong.
The atmosphere is not 70% Nitrogen. It's 78% Nitrogen. :

First of all, it's virtually impossible for the tire company to give you a 100% nitrogen-fill. This is because the tire starts out with ordinary atmosphere within it before they fill it with nitrogen.... It's NOT pure nitrogen in your tire.
IF anyone thinks about this... if you start out with ordinary compressed air (78% N)... and if the tire later has a 5 psi drop and needs "topping off" with additional ordinary compressed air.... then you now have MORE THAN 90% Nitrogen!
In fact, assuming a 5 psi loss of air each time they're checked, with only 5 such checking/top-offs, the tire has in excess of 98% pure nitrogen.

Why anyone would pay for this is beyond me.

(The major reason to use nitrogen is to eliminate moisture. Compressed air delivered thru a paint-gun de-humidifier pretty much does that anyway. As for the secondary reason ...(oxygen deteriorates tires and has a higher leak-rate)... your re-filling purifies the content by replacing any leaked-out oxygen with 78% Nitrogen in the refill.... and besides that, you will wear those tires out long before the oxygen inside them causes any measureable harm. In addition.. what will you do to avoid the 19% atmospheric oxygen on the outside of the tire?

Save your money for the next set of tires.

[DaveP]

2x Boxite!

DaveP

[Offack]

I posted to a thread A couple months ago, can't remember, I'm allowed I just got my Medicare card, that touched on this . I contacted Maxxis asking this same question, and the reply was in so many words, buy the tire rated for your rig, any rating above and beyond ,because of excess tire weight , would cause extra heat and could lead to tire failure. I would think running lower pressure than recommended shouldn't be a good idea. But check out Maxxis website....ask the pros.....they got back to me in 24 hrs!
Good luck, drive safe.
Rick
By the by, I have 25 ft FC.....with Maxxis 8008 d rated. Just completed coast to coast ,out and back, absolutely no problems with Maxxis

[Larry C]

Originally Posted by Boxite

Well, Larry... You're wrong.
The atmosphere is not 70% Nitrogen. It's 78% Nitrogen. :

First of all, it's virtually impossible for the tire company to give you a 100% nitrogen-fill. This is because the tire starts out with ordinary atmosphere within it before they fill it with nitrogen.... It's NOT pure nitrogen in your tire.
IF anyone thinks about this... if you start out with ordinary compressed air (78% N)... and if the tire later has a 5 psi drop and needs "topping off" with additional ordinary compressed air.... then you now have MORE THAN 90% Nitrogen!
In fact, assuming a 5 psi loss of air each time they're checked, with only 5 such checking/top-offs, the tire has in excess of 98% pure nitrogen.

Why anyone would pay for this is beyond me.




(The major reason to use nitrogen is to eliminate moisture. Compressed air delivered thru a paint-gun de-humidifier pretty much does that anyway. As for the secondary reason ...(oxygen deteriorates tires and has a higher leak-rate)... your re-filling purifies the content by replacing any leaked-out oxygen with 78% Nitrogen in the refill.... and besides that, you will wear those tires out long before the oxygen inside them causes any measureable harm. In addition.. what will you do to avoid the 19% atmospheric oxygen on the outside of the tire?

Save your money for the next set of tires.

Wow! Thanks for the 8% correction! I'm impressed, apparently you have a lot more insight than I....

Larry C

[SteveSueMac]

Originally Posted by Boxite

....what will you do to avoid the 19% atmospheric oxygen on the outside of the tire?

I'm confused...if 78% of the atmosphere is nitrogen, what's the other "19%"? 😜

[franklyfrank]

Originally Posted by Larry C

I would think that the main reason to go to load range E tires would for the increased weight capacity. In order to realize that increase capacity the maximum recommended pressure is 80 psi for load range E tires.

If you inflate to 65, you might have well stayed with your GYMs and inflated them to 65 psi..

Some people deliberately under inflate by a few pounds to "compensate" for increase tire pressure due to heat build up.....all they are doing is starting out with an under inflated tire, which will be more prone to failure because there will be more heat build up.

Some people drink the Kool Aid about nitrogen instead of compressed air....the air we breath is 70% nitrogen, you've got to be kidding me if you think that additional 30% nitrogen is going to make a difference? The theory is that nitrogen doesn't expand as quickly as compressed air in high temps......maybe so, maybe not......at any rate it's a waste of dollars.

People should stop trying to read more into this problem than exists....

For whatever it's worth..

Larry C

Thank You for the chemistry lesson. It was a surprise to me and you make a valid point.

[wvstreamer]

Maxxis needs bigger dealer network. In Myrtle Beach...separated GYM caught in time...thought about Maxxis but couldn't find them. Installing a couple of Mastertrack 225 × 15 E tires. After vacation I can make a better plan for the 03 Classic.
I'm just happy I caught the problem. I give my tires a good look quite often. My experience has shown this can save a lot of sadness.
Dave

[jimmini]

Do you know that the commercial airliners you fly on are required by the US FAA to service their tires with nitrogen?
"They use nitrogen because nitrogen gas is MOSTLY inert ,meaning that it requires more energy to react with other substances. this is important because at elevated temperatures, oxygen react with rubber"
Also nitrogen has larger molecules and will not leak out through the rubber as fast so it hold it pressure longer.
Google why service tires with nitrogen.

[BoldAdventure]

Current Air pressure is 34.3 Hg